As an apparatus for reducing vibration noise originated by rotating equipment such as a vehicle engine, an active vibration noise control apparatus using an adaptive notch filter is known. In such a conventional active vibration noise control apparatus, a control frequency is set to a vibration noise frequency identified by the rotational period of rotating equipment, and a control signal having an opposite phase of the vibration noise and having the control frequency is generated, and is output as a secondary vibration noise that is to be interfered with the vibration noise, so that the vibration noise is reduced.
Here, in a case where a frequency mismatch between an actual vibration noise frequency and the control frequency occurs owing to a measurement error and a signal delay, etc., of a rotation period sensor of rotating equipment, a problem arises in that a reduction effect on the vibration noise is weakened.
For addressing such a problem, for example, in Patent Document 1, a method is disclosed in which the control frequency is corrected in accordance with coefficient behavior of the adaptive notch filter.